This invention relates to a process for manufacturing colored contact lenses. More specifically it relates to a process for manufacturing contact lenses which contain a sufficient amount of added colorant to effect a change in the tint or color of the wearers eye while at the same time permitting visualization of the natural anatomy of the iris. The process produces lenses which do not significantly decrease the oxygen permeability of the uncolored contact lens. The invention also relates to colored contact lenses produced by the process.
Colored lenses currently on the market contain a tint throughout the entire section of the lens that covers the iris. While such lenses are capable of enhancing existing eye color or changing the color of light-colored eyes, they are not capable of causing fundamental color changes, for example, from dark brown to light blue.
Wichterle, in U.S. Pat. No. 3,679,504, dated July 25, 1972, discloses a contact lens having an opaque colorant covering the entire iris. While Wichterle's lenses are capable of causing a fundamental color change, the result will be an unnatural appearance unless a pattern in the opaque colorant is very artisticallly drawn or reproduced by expensive photographic means. This is so because the natural appearance of the iris is not a simple solid color, but a structure comprising many shapes and different colors. Moreover, Wichterle's opaque pattern reduces the amount of oxygen transmitted through the lens to the extent that the entire iris section is covered by the opaque colorant.
Urbach, in U.S. Pat. D. 211,757 dated July 23, 1968, discloses a contact lens with a portion of the iris section covered by an ornamental design. Substantial color change cannot be obtained by Urbach because only a portion of the iris is covered by the design.